The US is accusing Chinese spies and their recruited hackers of conspiring to steal trade secrets

The Justice Department filed charges on Tuesday against ten Chinese spies, hackers and others accused of pledging to steal sensitive commercial airlines and other secrets from US and European companies.

The indictment marks the third time since September that the United States has filed charges against Chinese intelligence officials and their recruits for stealing American intellectual property.

"This is just the beginning," Deputy Attorney General John Demers said. "Together with our federal partners, we will step up our efforts to protect America's ingenuity and investment."

The alleged conspiracy lasted at least five years since 2010, focusing on the theft of the technology of a turbofan engine used in US and European commercial aircraft. The engine was developed in a partnership between a French company based in Suzhou, China, and a US company.

Neither company was identified in the indictment and none of the suspected conspirators are in custody in the United States.

The indictment was issued on October 25 in the Southern District of California.

The defendants hacked the French company as well as companies in Arizona, Massachusetts, and Oregon that had made engine parts, officials said. At the time of the attack, a Chinese state-owned airline developed a comparable commercial jet engine.

[U.S., China vow not to engage in economic cyberespionage]

The alleged hijacking of trade secrets in favor of a Chinese company took place before Beijing pledged to Washington in September 2015 not to engage in such espionage. Experts say that since then China's cyber-based commercial espionage has been resumed, especially by the Ministry of State Security [MSS], which conducts non-military foreign espionage and domestic counter-espionage.

Two of the defendants, Zha Rong and Chai Meng, are officers from the Ministry of State Security of Jiangsu Province [JSSD], a provincial arm of the MSS.

Zha Rong is accused of directing the interference in the French company. Chai Meng, also known as "Cobain," co-ordinated the hackers and activities of two Chinese employees of the French company, who were also charged with their role in facilitating technology theft, US officials claimed. These employees, Gu Gen and Tian Xi, worked in the office in Suzhou.

According to the indictment, in January 2014 Tian received malware from his MSS handler and installed it on a corporate computer. A month later, Gu, who oversees information security at the company's Suzhou office in the French company, warned his colleagues that law enforcement overseas authorities notified the company about the malware, US prosecutors said.

As a result, two defendants removed evidence linking the malware to an account controlled by Chinese government officials, prosecutors said.

[In a first, a Chinese spy is extradited to the U.S. after stealing technology secrets, Justice Dept. says]

The first alleged hack took place in January 2010 when the defendants compromised Capstone Turbine, a Los Angeles-based gas turbine maker, to steal data and use its website to distribute malware.

Other hacking attempts followed, including against an unidentified computer company in San Diego, whose network was repeatedly abused and caused thousands of dollars in damage, prosecutors said. In this conspiracy, the prosecutor, Zhang Zhang-gui, a hacker operating on the instructions of provincial MSS, said his friend Li Xiao was malware developed by the activists who hacked the Capstone turbine. With this malware, Li was able to hack San Diego, prosecutors claimed.

Earlier this month, the Department of Justice announced that an MSS intelligence officer had been extradited to the Southern District of Ohio for attempting to steal business secrets related to aircraft engines. Last month, a grand jury convicted a US Army lawyer accused of acting as an agent of a JSSD spy.